Volume 7, Issue 4 e70066

RESEARCH ARTICLE

Open Access

Palmyra Palm Shell (Borassus flabellifer) Properties Part 1: Insights Into Its Physical and Chemical Properties

Md Atiqur Rahman,

Corresponding Author

Md Atiqur Rahman

[email protected]

orcid.org/0009-0009-5694-4709

Institute for Materials Research and Innovation, University of Bolton, Bolton, UK

Correspondence: Md Atiqur Rahman ([email protected])

Contribution: Conceptualization, Methodology, Formal analysis, Resources, Writing - original draft, Funding acquisition, Investigation, Software, Data curation, Visualization

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Mamadou Ndiaye,

Mamadou Ndiaye

Institute for Materials Research and Innovation, University of Bolton, Bolton, UK

Contribution: Supervision, Project administration, Writing - review & editing, Validation

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Bartosz Weclawski,

Bartosz Weclawski

Institute for Materials Research and Innovation, University of Bolton, Bolton, UK

Contribution: Writing - review & editing, Investigation, Supervision, Visualization, Validation, Project administration, Methodology

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Md Atiqur Rahman,

Corresponding Author

Md Atiqur Rahman

[email protected]

orcid.org/0009-0009-5694-4709

Institute for Materials Research and Innovation, University of Bolton, Bolton, UK

Correspondence: Md Atiqur Rahman ([email protected])

Contribution: Conceptualization, Methodology, Formal analysis, Resources, Writing - original draft, Funding acquisition, Investigation, Software, Data curation, Visualization

Search for more papers by this author

Mamadou Ndiaye,

Mamadou Ndiaye

Institute for Materials Research and Innovation, University of Bolton, Bolton, UK

Contribution: Supervision, Project administration, Writing - review & editing, Validation

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Bartosz Weclawski,

Bartosz Weclawski

Institute for Materials Research and Innovation, University of Bolton, Bolton, UK

Contribution: Writing - review & editing, Investigation, Supervision, Visualization, Validation, Project administration, Methodology

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First published: 30 March 2025

https://doi.org/10.1002/eng2.70066

Citations: 1

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ABSTRACT

Bio-based materials are gaining importance in engineering due to their availability, recyclability, and eco-friendliness. Among them, Borassus flabellifer (Palmyra palm) fruit shell (husk) is an underutilized biofiber in Bangladesh, currently limited to disposal or waste-to-energy applications despite its potential for high-value uses. This study explores the physical, chemical, and microstructural properties of untreated Borassus flabellifer husk to evaluate its suitability as a sustainable material for engineering applications. The physical properties, including density, water absorption, moisture regain, and porosity, were assessed according to BS EN ISO 1183-1:2019, ASTM D750, ASTM D2654-22, and ISO 2738 standards. The husk was found to be significantly lighter than its fine as well as coarse fibers and conventional natural fibers like jute, flax, and sisal, making it ideal for lightweight engineering designs. FTIR analysis (qualitatively) revealed the presence of cellulose, hemicellulose, and lignin, which contribute to its mechanical strength, water absorption, and thermal insulation properties, respectively. SEM analysis further demonstrated a cross-linked, porous, and tubular fiber structure, enhancing its thermal and sound insulation features. The findings suggest untreated Borassus flabellifer husk can be a promising alternative for applications requiring lightweight, thermally, and acoustically insulating materials. While its moisture and water resistance outperform some biofibers, chemical treatments could enhance these properties further. To maximize its potential, efficient collection and supply chain systems are essential for industrial-scale production. Harnessing this abundant resource could support sustainable development while encouraging the cultivation and preservation of Borassus flabellifer trees.

1 Introduction

Global environmental concerns have driven the scientific community to explore eco-friendly and renewable natural fibers as alternatives to synthetic ones, due to their superior properties. Prolonged use of synthetic fibers has been linked to serious health risks, including cancer and skin disorders. Additionally, synthetic fibers are non-biodegradable and have limited recyclability, which worsens environmental challenges [1, 2]. Furthermore, Siciliano and co-researchers [3] stated that adopting bio-based low-carbon goods might reduce CO₂ emissions from the materials' production process by more than 80%. It has been discovered that the disposal of synthetic fiber-based composite materials is a serious problem at the conclusion of the life cycle process, and during incineration, roughly 50% of the entire volume remains as a residue (unburned) [4].

As global temperatures and greenhouse gas emissions continue to rise, the United Nations Environment Programme's (UNEP) latest Emissions Gap Report finds that current Paris Agreement pledges put the world on track for a 2.5°C–2.9°C temperature rise above pre-industrial levels this century, highlighting the urgent need for increased climate action [5]. In accordance with this agreement, European Union (EU) members have vowed to put the EU on track to become the first climate-neutral economy and society by 2050, and the EU submitted its long-term carbon emission reduction strategy and vowed to cut emissions by at least 55% by 2030 compared to 1990 levels [6, 7]. Furthermore, the EU agreed to keep global average temperature rise to well below 2°C above pre-industrial levels, with efforts to limit it to 1.5°C [8].

To encounter the aforementioned context, natural fibers can play a crucial role in manufacturing green materials. The non-biodegradable qualities of synthetic fibers are causing global problems in reducing consumption. Hence, the industrial and academic sectors are increasingly showing an increased interest in natural fiber-based products. Natural fibers and bio-waste could be ideal alternatives to petroleum-based plastics since they are readily available, recyclable, and eco-friendly, Mohanty, Misra et al. [9], Mohanty, Amar et al. [10], Kumar et al. [4] reported that in 2010, the global natural fiber polymer composite material market had the highest value of USD289.3 million in 2010 and is expected to be increased by USD531.3 million in the next 10 to 12 years. Whereas Siciliano et al. [3] suggested that the global market for bio-based insulation is expected to reach USD 229 million by 2027, with a compound annual growth rate of 23.1% from 2022 to 2027.

Natural lignocellulosic fibers, like jute, flax, sisal, coir, palm, and so on, contain cellulose, hemicellulose, and lignin [11]. Cellulose is a primary structure of the cell wall. Cellulose has a crystalline structure that gives high strength to the plant. It has a long polymer chain with a high degree of polymerization and high molecular weight. Hemicellulose has a random unshaped structure that gives low strength and a low degree of polymerization. Lignin is a complex branched polymer of phenyl propane and is an important part of the plant's secondary cell walls. Lignin acts as a bonding agent for cellulose fibers that hold neighbor cells together, and its thermal durability is better than that of cellulose and hemicellulose [4, 12-15]. Nevertheless, the variation in the properties of any natural fibers is primarily attributed to their origin, climatic conditions, and growth period, leading to non-uniformity in physical properties along their length [16-18].

Palmyra Palm is a species of Borassus flabellifer, which belongs to the palm (Arecaceae) family. It contains over seven kinds, depending on the tree structure and tropical zone where it is planted. This is often known as the Asian palm, is the most significant of these species and has a wide range of commercial applications [17, 19]. For example, the leaf has long been used for fuel and thatching material and for weaving baskets, mats, boxes, caps, fans, toys, country umbrellas, etc. [20-22]. Fruits are being used in the production of jelly, cordials, ice cream, pastries, jams, drinks, and toffee, and the apple pulp can help treat skin inflammations. It treats nausea, vomiting, and worm infestation [16, 21, 23]. The trunk has been used as wood for construction and furniture and is also considered raw material for making wharf pilings into pillars, beams, and rafters [21, 22]. The tree root has been used to treat some respiratory illnesses since it is diuretic and anthelmintic. Nevertheless, the husk has been considered agricultural waste and used as fuel for cooking food in rural Bangladesh [24], which adversely affects the environment.

Borassus fibers are primarily harvested from the fruit of the Borassus flabellifer palm tree. However, they can also be extracted from the leaf and bark through mechanical and water retting methods. The properties of these fibers vary depending on the part of the plant from which they are sourced—whether from the fruit, sprouts, or leafstalks. This variation affects the fiber aspect ratio, a key factor influencing the performance of composite materials [25, 26]. Therefore, many researchers investigated the physical and chemical properties of Borassus fine and coarse fibers to evaluate their feasibility as an alternative material to existing conventional biofiber, such as jute, flax, sisal, coir, and hemp, to promote sustainable development. Saravanya and co-workers [27] extracted fiber from Borassus sprouts using manual and water retting techniques, and the densities were found to be 1.47 and 1.36 g/cm³, respectively, while Boopathi and co-workers [28] extracted fiber from Borassus fruit and found the density to be 1.26 g/cm³. Balakrishna and co-researchers [29] found that the density of the Borassus leafstalks was 0.7 g/cm³. The reported composition of Borassus flabellifer lignocellulosic fibers includes cellulose (45%–70%), hemicellulose (14%–32%), lignin (5%–30%) and extractives that may offer distinct mechanical and thermal properties [19]. Table 1 summarizes the properties and composition of Borassus fiber as reported in the literature, and Figure 1 shows the Borassus fruit shells (husks).

TABLE 1. Properties and composition of Borassus flabellifer fiber from literature.

Parts of the plant	Density (g/cm³)	Cellulose (%)	Hemicellulose (%)	Lignin (%)	Reference
		Composition
Fruit	—	50	—	—	[30]
Fruit	—	45.67 [Coarse] 53.40 [Fine]	32.76 [Coarse] 29.60 [Fine]	21.53 [Coarse] 17 [Fine]	[31]
Sprouts	1.47 [Manual] 1.36 [Water retting]	61.72 [Manual] 55.63 [Water retting]	—	23.25 [Manual] 30.66 [Water retting]	[27]
Fruit	—	70	14	11	[32]
Fruit	—	53.40 [Fine] 45.67 [Coarse]	—	—	[33]
Fruit	—	53.40	29.60	17	([34]; [35]; [36])

Details are in the caption following the image — **FIGURE 1**
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(A) Palmyra palm fruit, (B) cut-off the Palmyra palm fruit, (C) Palmyra palm fruit shell (husk).

While from the engineering material perspective, low density and porous properties are desirable for manufacturing lightweight insulators, yet low moisture as well as water absorption is also required because a higher sorption value deteriorates material mechanical properties.

Density and porosity are fundamental physical properties of any materials. While evaluating the mechanical performance of any dynamic designs, such as automobiles and aircraft, density is arguably the most important factor that defines the potential application of the fiber as a lightweight engineering material [37, 38], and porosity content is significant for the thermal insulation property [39-42]. The density of homogeneous solid materials is relatively easy to determine, as it only requires measurements of weight (or mass) and volume. However, measuring the density of natural fibers is more complex due to their porous structure and diverse geometry. Currently, there is no standardized testing method for determining the density of natural fibers in the industry [43]. They carried out density measurement tests on oilseed flax fiber and found the density in the range of 1.4–1.6 g/cm³. Nevertheless, they recommended selecting any fluid with low viscosity and surface tension, because it coats the fiber well, and it allows the fiber to sink into the fluid and be easily immersed. Amiri et al. [44] carried out density measurement experiments on flax fiber and found the density within the common range of 1.28–1.5 g/cm³, whereas Huo and co-workers [45] used the Archimedes method with distilled water as the immersion liquid and found the density of linen flax fiber to be 1.42 g/cm³. They finally recommended two methods: Archimedes (with the use of canola oil as immersion fluid) and helium pycnometry for their accuracy and reliability.

De Kerariou and co-researchers [46] investigated the impact of the porosity of flax fiber using scanning electron microscopy (SEM), ultrasonic C-scans, and gravimetric analysis. They reported that gravimetric adherence to Archimedean law using ethanol provides consistent and reliable results compared to the other two methods mentioned earlier. They revealed that the hygroexpansion is not substantially affected by changes in porosity—the lower the porosity, the slower the moisture ingress, and the tensile strength and stiffness decrease with the increase of void content. Researchers [47] investigated porosity using the toluene displacement method (using pycnometry) of pea (Pisum sativum) seed and found the porosity to be 40.32%.

Water absorption is an important ground for the degradation in the mechanical performance of the natural fiber and composites made of this, which resists them from being used in outdoor applications. Nevertheless, water absorbency is a key quality in textile fibers as it determines comfort properties in textile materials due to its influence on textile characteristics such as stiffness, frictional-mechanical properties, and electrical properties [11]. Additionally, the water absorption of fibers helps regulate humidity and improve the thermal and hygroscopic characteristics of buildings [48]. Sahu and Gupta [49] reviewed the effect of water absorption impact on material properties made of bio-fibers. They reported that the hydrophilic nature of cellulosic fibers is due to the hydroxyl groups in hemicellulose, cellulose, and lignin, which attract water through hydrogen bonding. Hemicellulose is the primary contributor to water absorption, followed by amorphous cellulose, lignin, and crystalline cellulose. Water absorption in biofiber-based composites follows a Fickian diffusion process at room temperature, but a non-Fickian process occurs at higher temperatures. The water absorption behavior is typically measured using ASTM D570, based on Archimedes' fluid displacement principle. Adebayo et al. [50] carried out a water absorption test on wood plastic composite as per ASTM D570, and they discovered that the tendency of cellulose at the filler-matrix interface to expand in the presence of water or moisture causes a shear stress at the interface, promoting ultimate debonding of the fillers and resulting in a loss in tensile strength. Hussain et al. [48] analyzed the effect of water absorption on tropical fibers, such as palm oil flower fibers, palm oil fruit fibers, sugarcane bagasse, coconut coir, and banana spine, and found that the water absorption was about 1–2 times their mass since natural fibers are hydrophilic in the presence of hemicellulose. Swelling and shrinkage of fibers occur during the interaction of fibers with water and drying, which induces voids in composites and affects their strength and performance.

The natural fibers are long-lasting, but when extracted by different mediums and different methods, they show different characteristics in the presence of moisture. Different natural fibers have different moisture absorption rates and different behaviors after moisture absorption [51]. Yalcin and co-workers [47] investigated the moisture absorption of pea (Pisum sativum) seeds with pycnometry using toluene and found the moisture content to be 35.08%. Sudhakara et al. [52] carried out an experiment on Borassus fine fiber-based composites and compared them with jute, sisal, and coir-based composites in terms of moisture and water absorption properties. They discovered that moisture uptake increases for Borassus fiber-based composites as fiber loading increases due to an increase in voids and cellulose content in the fiber, whereas water absorption in Borassus fiber-based composites is slightly higher than that of coir-based composites but lower than for jute and sisal-based composites. Boopathi and co-researchers [28] carried out an experiment on untreated (raw) Borassus fruit fiber and found the moisture content to be 8.04% in accordance with ASTM D2654-22 standards.

Fourier-transform infrared spectroscopy (FTIR) has been used in many studies to qualitatively confirm chemical changes caused by chemical reactions [13]. Previous studies [31, 33, 53] of FTIR on untreated Borassus fine fibers were carried out by dispersing the powdered fiber samples on KBr pellets at room temperature to analyze chemical compositions qualitatively and found the presence of three significant compositions, such as cellulose, hemicellulose, and lignin corresponding to hydroxyl (OH), alkyl (CH), carbonyl (CO), carboxyl (COOH) ether (COC) etc. at different wavenumbers, which arguably influence the fiber properties.

Most previous studies have focused primarily on the fine and coarse fibers of Borassus, with limited research conducted on Borassus husk fibers. Preliminary investigations into the thermal and mechanical properties of Borassus husk fibers have already been reported by the authors [54]. This paper presents an experimental study on the physical properties of untreated Borassus flabellifer husk fiber, including density (BS EN ISO 1183-1:2019), porosity (ISO 2738), water absorption (ASTM D 750) and moisture regain (ASTM D2654-22). It also examines its chemical properties using FTIR (ASTM E168-06 and ASTM E1252-98) and morphological characteristics through scanning electron microscopy (SEM). The study evaluates the potential of this fiber as an innovative bio-material for next-generation engineering applications.

2 Materials and Methods

Fruit shells of the Palmyra Palm (Borassus flabellifer) were collected from rural areas in Bogura, Bangladesh. The shells were cut and then thoroughly cleaned using a water-retting process, which is arguably the most widely used method [55]. Afterwards, the shells (Figure 2A) were sun-dried for several days and chopped into small pieces (Figure 2B,C) and prepared for physical and morphological experiments. Furthermore, they were crushed into powder (Figure 2E) using an electric blender (Figure 2D) to carry out chemical analysis. Figure 2 briefly represents the Borassus husk fiber preparation procedure.

2.1 Scanning Electron Microscopy (SEM)

A Hitachi S-3400N SEM was used to visualize the surface morphology of the shell. All the samples were mounted on aluminum posts using carbon conductive adhesive tape. Samples were sputter-coated before SEM analysis with a conductive gold layer using a Quorum Technologies SC7620 coater since biofibers are non-conductive. A low electron beam energy of 2–10 keV was used.

2.2 Fourier Transform Infrared Spectroscopy (FTIR)

Pellets were made with dried fibers, using potassium bromide (KBr) at a 2% concentration. The FTIR spectra of the untreated samples were acquired in the 4000–400 cm⁻¹ range, with 36 scans at a resolution of 4 cm⁻¹ using a Thermo Scientific Nicolet iS10 FTIR spectrometer and using ASTM E168-06 and ASTM E1252-98 standards in previous studies [35, 53, 56] to analyze chemical compositions of untreated Borassus husk fiber qualitatively.

2.3 Density Measurement

The densities of the fibers were determined using the pycnometer method with distilled water as the immersion liquid, following the standards BS EN ISO 1183-1:2019 and ASTM D792, which are based on Archimedes' fluid displacement theory. Before testing, the samples were dried in an oven for 24 h at 50°C, as specified in ASTM D570-98, to remove moisture. After drying, the samples were cooled to room temperature in a desiccator. The mass was measured with an accuracy of 0.001 g. The experiments were carried out 10 times, followed by determining the average value along with the standard deviation for repeatability and reproducibility. The density of the fruit shell was then calculated using the following equation used in previous studies [57, 58]:

{\rho}_s=\frac{m_s\times {\rho}_l}{m_1-{m}_2}

(1)

where, ρ_s is the density (g/cm³), m_s is the apparent mass of the sample (g), m₁ is the apparent mass of the liquid to fill the pycnometer (g), m₂ is the apparent mass of the liquid to fill the pycnometer containing the sample, and ρ_l is the density of the immersion liquid at room temperature (g/cm³).

2.4 Water Absorption

A 24-h immersion method [ASTM D750] was used to measure the water sorption. Before the test, the samples were placed inside an oven at 50°C for 24 h to eliminate all moisture [52]. The samples were then cooled and neutralized to room temperature in a desiccator. The specimens were then immersed in a transparent (glass) container with distilled water and kept at room temperature for 24 h. The mass was measured to the closest 0.001 g in all weight measurement cases. The experiments were carried out 10 times, followed by determining the average value along with the standard deviation for repeatability and reproducibility. The water absorption of the seed shell was calculated from the following equation used by previous researchers [50, 59, 60].

{W}_a=\frac{W_i-{W}_f}{\ {W}_i}\times 100

(2)

where, W_a is the water absorption (%), W_f is the final weight of the specimen (g), and W_i is the initial dry weight of the samples (g).

2.5 Porosity

The porosity is the void presence in the testing articles. Archimedean porosimetry [ISO 2738] is the most widely used method to measure open porosity, used in previous studies [61-63]. It is based on Archimedes' buoyancy principle. After water absorption, the porosity of the samples can then be calculated analytically, as distilled water (liquid) has filled the porous (void) space in the samples. Palm seed density is lower than that of other plant-based fibers due to sample porosity. The porosity of the samples has been calculated from the following equations:

{V}_p=\frac{M_w-{M}_d}{\rho_w}

(3)

\mathrm{\O}\left(\%\right)=\frac{\ {V}_p}{V_b}\times 100

(4)

where V_p is the volume of water inside the sample, ρ_w is the density of the water, M_w is the wet mass, and M_d is the dry mass of the sample. Furthermore,

\mathrm{\O}

and V_b are the porosity and the dry sample volume, respectively.

2.6 Moisture Regain

The oven-drying method [ASTM D2654-22] was used to carry out the moisture regain test. Borassus fruit shell is hydrophilic. The samples were dried in an oven at 105°C for 4 h [11] and cooled in a desiccator at room temperature until they stabilized, after which the dry weight was measured with a precision of ±0.001 g. The weight difference between samples reflects their moisture content [28]. The experiments were carried out 10 times, followed by determining the average value along with the standard deviation for repeatability and reproducibility. The moisture regain of samples was calculated from the following equation used in previous studies [11, 60]:

{M}_c=\left[\frac{\ {M}_w-{M}_d\ }{\ {M}_w}\right]\times 100

(5)

where M_c is the moisture uptake (%), M_w is the wet mass of the specimens (g), and M_d is the dry mass of the samples (g).

3 Results and Discussion

3.1 Scanning Electron Microscopy (SEM)

Figure 3 depicts the outcomes from the SEM experiment: the fibers appear to be elongated and have an uneven and rough surface, which is also found by Boopathi et al. [28] and Sarasini et al. [30]. However, other studies [27, 53] also found that the untreated fiber and Palmyra sprout fiber surfaces were smooth and compact. The arrangement seems relatively parallel (Figure 3A), suggesting that the fibers lie somewhat aligned, which is also found for wood apple shell material [64]. Furthermore, the fiber diameter is non-uniform, ranging from 150 to 300 μm (Figure 3B), and it is cylindrically hollow (Figure 3C). Researchers [3, 40, 42] suggested that porous structures can successfully reduce sound energy by increasing air-pore wall friction while also decreasing thermal transmission by reducing the material's cross-sectional solid area and increasing the tortuosity of heat transfer channels. Mawardi et al. [65] suggested that voids or pores have a direct connection with density and thermal conductivity properties, and they revealed that the density and heat conductivity were found to be less with increasing pores (voids) in the natural fibers. Figure 3 D reveals the cross-section of the fiber that is covered with impurities and wax content, which can be removed through chemical treatment [30, 55, 66-69]. Nevertheless, the average fiber diameter was reported to be 241.18 μm [28] and 140 μm [19] for Borassus fine fiber. Whereas the diameters of relevant plant-based bio-fibers, such as jute, sisal, and ramie have been reported as 5–30 mm, 7–47 mm, and 7–80 mm, respectively, in the previous works [70, 71].

3.2 Fourier Transform Infrared Spectroscopy (FTIR)

The spectra of the untreated fibers in Figure 4 revealed a significant absorption band for inter-molecularly linked hydroxyl (OH) groups at around 3413 cm⁻¹. This observation provided evidence that the hydroxyl groups were engaged in hydrogen bonding. The CH stretching vibrations of the methylene/methylene units of all three ingredients were detected as a shoulder peak at 2920 cm,⁻¹ owing to aliphatic saturated molecules, such as cellulose and hemicellulose.

A wide, medium-intensity ester carbonyl vibration at 1734 cm⁻¹ was attributed to carbonyl (CO) stretching of acetyl groups in hemicellulose. The distinctive COC stretching vibration of hemicellulose ester groups was detected at 1252 cm⁻¹. Peaks at 1618 and 1637 cm⁻¹ are attributed to bending hydroxyl (OH) bonds that account for water absorption. The bands at 1509 and 1462 cm⁻¹ corresponded to aromatic CC ring stretching and CH deformation in the methyl, methylene, and methoxyl groups of lignin. The bands at 1426, 1377, and 1320 cm⁻¹ correspond to the CH₂ scissoring, OH bending vibration, and CH asymmetric deformation of cellulose. The bands at 1162, 1109, and 1045 cm⁻¹ correspond to the COC, CO, and CC stretching of cellulose. The analysis has been found to be consistent with previous research works [33, 34, 53]. Kabir et al. [14] reported that cellulose is considered the major framework component of the fiber structure, covered by hemicellulose and lignin constituents and provides strength, stiffness, and structural stability of the fiber. In lignocellulosic fiber, the hydroxyl groups present in the amorphous hemicellulose and lignin initially give access for water molecules to penetrate the fiber surface. Additionally, non-crystalline cellulose, with its nano-porous structure and exposed hydroxyl sites, affects the sorption process significantly [15]. Nevertheless, these compositions have also been found in conventional lignocellulosic fibers, such as jute, sisal, and flax, reported in previous works [71-74]. Moreover, the presence of hemicellulose, cellulose, and lignin contents has been suggested in the authors own work through TGA and DSC analysis [54].

3.3 Physical Properties and Moisture Interaction Characteristics

The density of the Borassus husk was found to be 0.74 ± 0.06 g/cm³, which is higher than its leafstalks' density, 0.70 g/cm³ [29] but less than its fine fiber (1.26 g/cm³) reported earlier. Dharmaratne et al. [12] found the density of brown coir fiber from Sri Lanka to be 1.02 g/cm³, using the pycnometry method. McNulty and co-researchers [75] used the pycnometry method to evaluate the density of grass. They used toluene and air as a reference fluids and found that the density of grass was 1.02 g/cm³ and 1.12 g/cm³, respectively. Hussain et al. [48] found that the density values of tropical fibers, such as palm oil flower fibers, palm oil fruit fibers, sugarcane bagasse, coconut coir, and banana spine, range from 0.79–1.36 g/cm³ and are influenced by lumen. Huo and co-workers [45] used the Archimedes method with distilled water as immersion liquid and found the density of linen flax fiber to be 1.42 g/cm³. The Borassus husk demonstrates a lower density, which can be linked to its higher porosity, as observed in the previous SEM analysis. This density is not only lower than that of synthetic fibers but also the lowest among common natural fibers, including jute (1.3–1.46 g/cm³), ramie (1.38–1.6 g/cm³), sisal (0.76–1.58 g/cm³), and hemp (1.47 g/cm³), as reported in the literature [71, 72, 76-78].

The water absorption of the samples was measured to be 46.58% ± 3.77%, and the moisture regain of the samples was found to be 4.41% ± 0.50%. The moisture regain of the raw Borassus fine fiber reported by Boopathi et al. [28] was 8.04%. While Kongdee et al. [11] found the water absorption of the cellulosic fibers, such as lyocell, viscose, and modal, to be 76%, 96%, and 71%, respectively, and the moisture regain found to be 11%, 12%, and 11%, respectively, the mean moisture content of the grass stem was found to be 83.4% [75]. Hill with co-researchers [79] carried out a comparative study on flax, jute, coir, cotton, and hemp on moisture and water absorption, and they found that jute (4.53%) and coir (4.14%) exhibited higher moisture contents compared to fibers having very low lignin levels, such as hemp (3.79%), flax (3.68%) and cotton (2.65%). They also suggested that cotton has the highest cellulose (94%), the lowest lignin (0%) and hemicellulose (6%), which can be the reason for the least moisture level.

The initial hypothesis of this study is that biomass with a higher proportion of hygroscopic components (such as hemicellulose and amorphous cellulose) compared to hydrophobic components (such as lignin and crystalline cellulose) will exhibit different equilibrium moisture content, primarily due to the accessibility of hydroxyl groups [15]. Hemicelluloses have a more open structure than cellulose and are thus more hydrophilic and soluble in water, but the sensitivity to water is drastically reduced when cellulose stacks to create crystalline areas [12, 14, 49, 51, 80]. Berthold with co-workers [81] reported that the higher values obtained for water absorption are attributed to the fact that water sorption in fibers is not limited to the pores alone; it can also occur on the surface of the fiber microstructures. Therefore, the observed water retention is the result of bound water, pore water, and surface water present within the fibers.

One of the primary reasons for the degradation of the mechanical properties of polymeric composites is the absorption of water by the fibers. This issue is particularly significant when water-permeable resins are used without incorporating fiber hydrophobic surface treatments or resin additives, limiting the composites' applications primarily to indoor environments. When fibers absorb water, the capillaries swell and expand, which activates microcracks. Water molecules then infiltrate the bulk matrix and travel along the fiber-matrix interface through capillary action, effectively acting as a bonding removal agent [50, 51].

Porosity was calculated, followed by the results obtained from the dry sample density and water absorption. The average porosity of Borassus husk fiber was found to be 34.55% ± 2.8%. Sacilik with co-workers [82] found the porosity of the hemp seed to be 46.5% and the cotton seed to be 41.1%. Yalcin with co-researchers [47] found the porosity of pea to be 38.64%. Kongdee et al. [11] investigated the pore volume of cellulosic fibers, such as lyocell, viscose, and modal, and found the pore sizes to be 0.59, 0.71, and 0.49 mL/g, respectively. Nevertheless, the earlier SEM analysis (Figure 3) revealed the porosity in the Borassus husk fiber, which can be linked with its low density. Porous structures are required for thermal insulation and noise reduction, such as for construction and cold-chain transportation in modern engineering applications [40, 42].

The low density, water absorption, and moisture regain can be attributed to hollow cylindrical porous tubes found in this research and previous studies [19, 83, 84]. The mechanical and thermal properties of untreated Borassus husk fibers have been studied in a separate work by the authors [54]. The findings indicate that these fibers show significant potential as an alternative biofiber for modern engineering applications that require materials with a porous structure, lightweight, promising strength, and thermal insulation properties. Nevertheless, high water absorption is a concern for mechanical strength to be compromised, which can be improved through chemical treatments [25, 85-87]. Table 2 summarizes all the experimental outcomes of untreated Borassus fruit shell (husk) fiber.

TABLE 2. Physical properties of untreated (raw) Borassus fruit shell (husk).

Physical properties	Standard	Mean value	Standard deviation, SD	Coefficient of variance, CV (%)
Density (g/cm³)	BS EN ISO 1183-1:2019	0.74	0.06	8.53
Water absorption (wt. %)	ASTM D 750	46.58	3.77	8.10
Porosity (wt. %)	ISO 2738	34.55	2.80	8.10
Moisture regain (wt. %)	ASTM D2654-22	4.41	0.50	11.39

4 Conclusion

This study examines the physical properties, such as density, water absorption, moisture regain, and porosity, of untreated Borassus flabellifer (Palmyra palm) fruit shell (husk) in accordance with BS EN ISO 1183-1:2019, ASTM D 750, ASTM D2654-22, and ISO 2738 standards, as well as its chemical properties following ASTM E168-06 and ASTM E1252-98 standards. The results of the investigation are presented below:

The density was found to be 0.74 g/cm³, which is lighter than its fine fiber (1.26 g/cm³) and other natural fibers, such as jute, flax, sisal, and hemp. This point to a potential utilization in lightweight engineering designs.
Water absorption (46.58%) and moisture regain (4.41%) values are also lower than comparable plant-based fibers, such as lyocell, viscose, and modal, which may improve the weathering resistance of processed materials.
The porosity of Borassus flabellifer husk was measured at 34.55%, which is lower than that of hemp seed (46.5%), cotton seed (41.1%), and pea. This lower porosity is associated with the material's low density and improved thermal insulation properties. The voids within the material act as scattering centers for phonons, thereby disrupting heat transfer and reducing the effective heat conduction volume of the material.
FTIR analysis confirms the presence of cellulose, hemicellulose, and lignin, as well as other lignocellulosic fibers, such as hemp, flax, sisal, ramie, and even Borassus fine as well as coarse fiber. Cellulose offers mechanical strength, lignin is for thermal insulation property, and hemicellulose is responsible for water absorption property.
The microstructure analysis from SEM reveals that the fibers are cross-linked, porous, and tubular, with diameters ranging from 150 to 300 μm. This diameter is smaller compared to fibers, such as jute, ramie, and sisal. The lower density of the material can be attributed to the presence of voids, as an increase in voids typically results in a decrease in density.

This study found that Borassus flabellifer husk has a lower density compared to its coarse and fine fibers. It also exhibits superior moisture and water resistance properties compared to some other bio-based materials. However, chemical treatments could be applied to further enhance its resistance to moisture and water. The porosity and cross-linked structures observed in SEM analysis suggest strong thermal and sound insulation properties, making it a potential competitor to conventional biofibers such as sisal, flax, and jute. These properties position it as a viable material for manufacturing engineering indoor components for cars, aircraft, and building facilities to promote sustainable development. It is important to note that the properties of biofibres vary significantly depending on factors such as environmental conditions, geographic origin, and maturity. Although Borassus flabellifer husk is locally abundant, establishing an efficient collection and supply chain system is essential to support its industrial-scale production and utilization.

Author Contributions

Md Atiqur Rahman: conceptualization, methodology, formal analysis, resources, writing – original draft, funding acquisition, investigation, software, data curation, visualization. Mamadou Ndiaye: supervision, project administration, writing – review and editing, validation. Bartosz Weclawski: writing – review and editing, investigation, supervision, visualization, validation, project administration, methodology.

Conflicts of Interest

The authors declare no conflicts of interest.

Open Research

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.

References

1S. Garriba, H. S. Jailani, C. A. Pandian, and P. Diwahar, “Effect of Water Retting on the Physical and Mechanical Properties of Lignocellulosic Fiber From Mariscus ligularis Plant,” International Journal of Biological Macromolecules 288 (2025): 138718.
10.1016/j.ijbiomac.2024.138718
CAS PubMed Web of Science® Google Scholar
2J. Tengsuthiwat, V. Raghunathan, V. Ayyappan, et al., “Lignocellulose Sustainable Composites From Agro-Waste Asparagus Bean Stem Fiber for Polymer Casting Applications: Effect of Fiber Treatment,” International Journal of Biological Macromolecules 278 (2024): 134884.
10.1016/j.ijbiomac.2024.134884
CAS PubMed Web of Science® Google Scholar
3A. P. Siciliano, X. Zhao, R. Fedderwitz, et al., “Sustainable Wood-Waste-Based Thermal Insulation Foam for Building Energy Efficiency,” Buildings 13, no. 4 (2023): 840.
10.3390/buildings13040840
Web of Science® Google Scholar
4S. Kumar, L. Prasad, V. K. Patel, et al., “Physical and Mechanical Properties of Natural Leaf Fiber-Reinforced Epoxy Polyester Composites,” Polymers 13, no. 9 (2021): 1369.
10.3390/polym13091369
CAS PubMed Web of Science® Google Scholar
5 UN Environment, “Nations Must Go Further Than Current Paris Pledges or Face Global Warming of 2.5–2.9C.” (2023), https://www.unep.org/news-and-stories/press-release/nations-must-go-further-current-paris-pledges-or-face-global-warming.
Google Scholar
6J. Dinneen, “Satellite Launched to Track Down Leaks of Potent Greenhouse Gas.” (2024), https://www.newscientist.com/article/2419765-satellite-launched-to-track-down-leaks-of-potent-greenhouse-gas/.
Google Scholar
7B. Plumer, “Climate Change Is Speeding Toward Catastrophe. The Next Decade Is Crucial, U.N. Panel Says.” NYTimes.com Feed (2023), https://global.factiva.com/en/du/article.asp?accessionno=NYTFEED020230320ej3k002pb.
Google Scholar
8 European Council, “Paris Agreement on Climate Change.” (2023), https://www.consilium.europa.eu/en/policies/climate-change/paris-agreement/.
Google Scholar
9A. K. Mohanty, M. A. Misra, and G. I. Hinrichsen, “Biofibres, Biodegradable Polymers and Biocomposites: An Overview,” Macromolecular Materials and Engineering 276, no. 1 (2000): 1–24.
10.1002/(SICI)1439-2054(20000301)276:1<1::AID-MAME1>3.0.CO;2-W
Web of Science® Google Scholar
10A. K. Mohanty, S. Vivekanandhan, J. Pin, and M. Misra, “Composites From Renewable and Sustainable Resources: Challenges and Innovations,” Science 362, no. 6414 (2018): 536–542.
10.1126/science.aat9072
CAS PubMed Web of Science® Google Scholar
11A. Kongdee, T. Bechtold, E. Burtscher, and M. Scheinecker, “The Influence of Wet/Dry Treatment on Pore Structure—The Correlation of Pore Parameters, Water Retention and Moisture Regain Values,” Carbohydrate Polymers 57, no. 1 (2004): 39–44.
10.1016/j.carbpol.2004.03.025
CAS Web of Science® Google Scholar
12P. D. Dharmaratne, H. Galabada, R. Jayasinghe, R. Nilmini, and R. U. Halwatura, “Characterization of Physical, Chemical and Mechanical Properties of Sri Lankan Coir Fibers,” Journal of Ecological Engineering 22, no. 6 (2021): 55–65.
10.12911/22998993/137364
Web of Science® Google Scholar
13H. W. Hussin, K. Abdan, M. S. Salit, and E. S. Bakar, “Physical Changes and FTIR Analysis of Kenaf Core Fiber Heat Treated in Air,” 2018.
Google Scholar
14M. M. Kabir, H. Wang, K. T. Lau, and F. Cardona, “Effects of Chemical Treatments on Hemp Fibre Structure,” Applied Surface Science 276 (2013): 13–23.
10.1016/j.apsusc.2013.02.086
CAS Web of Science® Google Scholar
15N. Sweygers, D. E. Depuydt, S. Eyley, et al., “Prediction of the Equilibrium Moisture Content Based on the Chemical Composition and Crystallinity of Natural Fibres,” Industrial Crops and Products 186 (2022): 115187.
10.1016/j.indcrop.2022.115187
CAS Web of Science® Google Scholar
16H. Jana and S. Jana, “Palmyra Palm: Importance in Indian Agriculture,” Rashtriya Krishi 12, no. 2 (2017): 35–40.
Google Scholar
17S. Kumari, R. Rani, S. Sengupta, A. Aftab, N. Kumari, and A. Aman, “Study of Genetic Variability of Palmya Palm on the Basis of Tree Morphology and Yield Parameters in Bihar,” International Journal of Current Microbiology and Applied Sciences 9 (2020): 2522–2528.
Google Scholar
18R. Shrestha, “A Review on Nutritional Properties of Palmyra Palm (Borassus flabellifer L.),” 2023.
Google Scholar
19J. K. Singh, A. K. Rout, and K. Kumari, “A Review on Borassus Flabellifer Lignocellulose Fiber Reinforced Polymer Composites,” Carbohydrate Polymers 262 (2021): 117929.
10.1016/j.carbpol.2021.117929
CAS PubMed Web of Science® Google Scholar
20A. J. Kora, “Leaves as Dining Plates, Food Wraps and Food Packing Material: Importance of Renewable Resources in Indian Culture,” Bulletin of the National Research Centre 43, no. 1 (2019): 1–15.
10.1186/s42269-019-0231-6
Google Scholar
21V. S. Ramachandran, K. Swarupanandan, and C. Renuka, “A Traditional Irrigation System Using Palmyra Palm (Borassus Flabellifer) in Kerala, India,” Palms 48, no. 4 (2004): 175–181.
Google Scholar
22S. Siju and K. K. Sabu, “Genetic Resources of Asian Palmyrah Palm (Borassus Flabellifer L.): A Comprehensive Review on Diversity, Characterization and Utilization,” Plant Genetic Resources 18, no. 6 (2020): 445–453.
10.1017/S1479262120000477
CAS Google Scholar
23P. C. Vengaiah, S. Kaleemullah, M. Madhava, A. Mani, and B. Sreekanth, “Palmyrah Fruit (Borassus Flabellifer L.): Source of Immunity and Healthy Food: A Review,” Pharma Innovation 10, no. 11 (2021): 1920–1925.
CAS Google Scholar
24M. Afroza Khatun, S. Sultana, H. Parvin Nur, and A. M. Sarwaruddin Chowdhury, “Physical, Mechanical, Thermal and Morphological Analysis of Date Palm Mat (DPM) and Palmyra Palm Fruit (PPF) Fiber Reinforced High Density Polyethylene Hybrid Composites,” Advanced Materials Science 4 (2019): 1–6.
Google Scholar
25P. Sahu and M. K. Gupta, “A Review on the Properties of Natural Fibres and Its Bio-Composites: Effect of Alkali Treatment,” Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 234, no. 1 (2020): 198–217.
10.1177/1464420719875163
Web of Science® Google Scholar
26V. K. Thakur, Green Composites From Natural Resources (CRC Press, 2013).
10.1201/b16076
Google Scholar
27K. S. Saravanya, S. Kavitha, and M. Parthiban, “Thermal Properties of Natural Fibres Extracted From Palmyra Sprouts,” Indian Journal of Fibre & Textile Research (IJFTR) 45, no. 4 (2021): 488–494.
Google Scholar
28L. Boopathi, P. S. Sampath, and K. Mylsamy, “Investigation of Physical, Chemical and Mechanical Properties of Raw and Alkali Treated Borassus Fruit Fiber,” Composites Part B: Engineering 43, no. 8 (2012): 3044–3052.
10.1016/j.compositesb.2012.05.002
CAS Web of Science® Google Scholar
29A. Balakrishna, D. N. Rao, and A. S. Rakesh, “Characterization and Modeling of Process Parameters on Tensile Strength of Short and Randomly Oriented Borassus Flabellifer (Asian Palmyra) Fiber Reinforced Composite,” Composites Part B: Engineering 55 (2013): 479–485.
10.1016/j.compositesb.2013.07.006
CAS Web of Science® Google Scholar
30F. Sarasini, J. Tirillò, D. Puglia, et al., “Biodegradable Polycaprolactone-Based Composites Reinforced With Ramie and Borassus Fibres,” Composite Structures 167 (2017): 20–29.
10.1016/j.compstruct.2017.01.071
Web of Science® Google Scholar
31K. O. Reddy, B. R. Guduri, and A. V. Rajulu, “Structural Characterization and Tensile Properties of Borassus Fruit Fibers,” Journal of Applied Polymer Science 114, no. 1 (2009): 603–611.
10.1002/app.30584
CAS Web of Science® Google Scholar
32Y. N. Marathe, A. T. Arun Torris, C. Ramesh, and M. V. Badiger, “Borassus Powder-Reinforced Poly (Lactic Acid) Composites With Improved Crystallization and Mechanical Properties,” Journal of Applied Polymer Science 136, no. 18 (2019): 47440.
10.1002/app.47440
Web of Science® Google Scholar
33C. U. Maheswari, K. O. Reddy, E. Muzenda, M. Shukla, and A. V. Rajulu, “A Comparative Study of Modified and Unmodified High-Density Polyethylene/Borassus Fiber Composites,” International Journal of Polymer Analysis and Characterization 18, no. 6 (2013): 439–450.
10.1080/1023666X.2013.814027
CAS Web of Science® Google Scholar
34K. Obi Reddy, M. Shukla, C. Uma Maheswari, and A. Varada Rajulu, “Mechanical and Physical Characterization of Sodium Hydroxide Treated Borassus Fruit Fibers,” Journal of Forestry Research 23 (2012): 667–674.
10.1007/s11676-012-0308-7
CAS Google Scholar
35K. O. Reddy, C. U. Maheswari, M. S. Dhlamini, et al., “Preparation and Characterization of Regenerated Cellulose Films Using Borassus Fruit Fibers and an Ionic Liquid,” Carbohydrate Polymers 160 (2017): 203–211.
10.1016/j.carbpol.2016.12.051
CAS PubMed Web of Science® Google Scholar
36K. O. Reddy, C. U. Maheswari, K. R. Reddy, M. Shukla, E. Muzenda, and A. V. Rajulu, “Effect of Chemical Treatment and Fiber Loading on Mechanical Properties of Borassus (Toddy Palm) Fiber/Epoxy Composites,” International Journal of Polymer Analysis and Characterization 20, no. 7 (2015): 612–626.
10.1080/1023666X.2015.1054084
CAS Web of Science® Google Scholar
37M. Z. Rahman, M. Rahman, T. Mahbub, M. Ashiquzzaman, S. Sagadevan, and M. E. Hoque, “Advanced Biopolymers for Automobile and Aviation Engineering Applications,” Journal of Polymer Research 30, no. 3 (2023): 106.
10.1007/s10965-023-03440-z
CAS Web of Science® Google Scholar
38A. Żarnowska, “Sustainability Assessment of a Sustainable Innovation for the Aviation Industry: Case Study of Bio Composites for Aircraft Interiors,” 2023.
Google Scholar
39R. Mirski, D. Dukarska, J. Walkiewicz, and A. Derkowski, “Waste Wood Particles From Primary Wood Processing as a Filler of Insulation PUR Foams,” Materials 14, no. 17 (2021): 4781.
10.3390/ma14174781
CAS PubMed Web of Science® Google Scholar
40L. Savio, R. Pennacchio, A. Patrucco, V. Manni, and D. Bosia, “Natural Fibre Insulation Materials: Use of Textile and Agri-Food Waste in a Circular Economy Perspective,” Materials Circular Economy 4, no. 1 (2022): 6.
10.1007/s42824-021-00043-1
Google Scholar
41H. Srinivasan, H. Arumugam, B. Krishnasamy, A. A. MI, A. Murugesan, and A. Muthukaruppan, “Desert Cotton and Areca Nut Husk Fibre Reinforced Hybridized Bio-Benzoxazine/Epoxy Bio-Composites: Thermal, Electrical and Acoustic Insulation Applications,” Construction and Building Materials 363 (2023): 129870.
10.1016/j.conbuildmat.2022.129870
CAS Web of Science® Google Scholar
42X. Zhao, Y. Liu, L. Zhao, et al., “A Scalable High-Porosity Wood for Sound Absorption and Thermal Insulation,” Nature Sustainability 6, no. 3 (2023): 306–315.
10.1038/s41893-022-01035-y
Web of Science® Google Scholar
43M. Truong, W. Zhong, S. Boyko, and M. Alcock, “A Comparative Study on Natural Fibre Density Measurement,” Journal of the Textile Institute 100, no. 6 (2009): 525–529.
10.1080/00405000801997595
Web of Science® Google Scholar
44A. Amiri, Z. Triplett, A. Moreira, N. Brezinka, M. Alcock, and C. A. Ulven, “Standard Density Measurement Method Development for Flax Fiber,” Industrial Crops and Products 96 (2017): 196–202.
10.1016/j.indcrop.2016.11.060
Web of Science® Google Scholar
45S. Huo, M. A. Fuqua, V. S. Chevali, and C. A. Ulven, “Effects of Natural Fiber Surface Treatments and Matrix Modification on Mechanical Properties of Their Composites,” SAE Intenational, no. 2 (2010): 1–10.
Google Scholar
46C. de Kergariou, A. le Duigou, V. Popineau, et al., “Measure of Porosity in Flax Fibres Reinforced Polylactic Acid Biocomposites,” Composites Part A: Applied Science and Manufacturing 141 (2021): 106183.
10.1016/j.compositesa.2020.106183
Google Scholar
47İ. Yalçın, C. Özarslan, and T. Akbaş, “Physical Properties of Pea (Pisum Sativum) Seed,” Journal of Food Engineering 79, no. 2 (2007): 731–735.
10.1016/j.jfoodeng.2006.02.039
Web of Science® Google Scholar
48M. Hussain, D. Levacher, N. Leblanc, et al., “Analysis of Physical and Mechanical Characteristics of Tropical Natural Fibers for Their Use in Civil Engineering Applications,” Journal of Natural Fibers 20, no. 1 (2023): 2164104.
10.1080/15440478.2022.2164104
Web of Science® Google Scholar
49P. Sahu and M. K. Gupta, “Water Absorption Behavior of Cellulosic Fibres Polymer Composites: A Review on Its Effects and Remedies,” Journal of Industrial Textiles 51, no. 5_suppl (2022): 7480S–7512S.
10.1177/1528083720974424
CAS Web of Science® Google Scholar
50G. Adebayo, A. Hassan, R. Yahya, N. Sarih, and K. Odesanya, “Effects of Water Absorption on the Tensile and Thermal Properties of Heat Treated Mangrove/High-Density Polyethylene Composites,” 2018.
Google Scholar
51A. A. Bachchan, P. P. Das, and V. Chaudhary, “Effect of Moisture Absorption on the Properties of Natural Fiber Reinforced Polymer Composites: A Review,” Materials Today Proceedings 49 (2022): 3403–3408.
10.1016/j.matpr.2021.02.812
CAS Google Scholar
52P. Sudhakara, D. Jagadeesh, Y. Wang, et al., “Fabrication of Borassus Fruit Lignocellulose Fiber/PP Composites and Comparison With Jute, Sisal and Coir Fibers,” Carbohydrate Polymers 98, no. 1 (2013): 1002–1010.
10.1016/j.carbpol.2013.06.080
CAS PubMed Web of Science® Google Scholar
53K. Obi Reddy, C. Uma Maheswari, M. Shukla, J. I. Song, and A. Varada Rajulu, “Tensile and Structural Characterization of Alkali Treated Borassus Fruit Fine Fibers,” Composites Part B: Engineering 44, no. 1 (2013): 433–438.
10.1016/j.compositesb.2012.04.075
CAS Web of Science® Google Scholar
54M. A. Rahman, M. Ndiaye, B. Weclawski, and P. Farrell, “Palmyra Palm Shell (Borassus flabellifer) Properties Part 2: Insights into Its Thermal and Mechanical Properties,” 2024a.
Google Scholar
55M. R. Sanjay, S. Siengchin, J. Parameswaranpillai, M. Jawaid, C. I. Pruncu, and A. Khan, “A Comprehensive Review of Techniques for Natural Fibers as Reinforcement in Composites: Preparation, Processing and Characterization,” Carbohydrate Polymers 207 (2019): 108–121.
10.1016/j.carbpol.2018.11.083
PubMed Web of Science® Google Scholar
56M. K. B. Bakri and E. Jayamani, “Comparative study of Functional Groups in Natural Fibers: Fourier Transform Infrared Analysis (FTIR),” 2016.
Google Scholar
57A. Pritchard, M. McCourt, M. Kearns, P. Martin, and E. Cunningham, “Process and Material Parameter Optimisation of Rotomoulded Polymer Foams,” Procedia Manufacturing 47 (2020): 991–997.
10.1016/j.promfg.2020.04.305
Google Scholar
58B. Soriano-Cuadrado, M. Á. Fontecha-Cámara, M. Mañas-Villar, I. Delgado-Blanca, and M. D. Ramírez-Rodríguez, “Mechanical, Thermal and Morphological Study of Bio-Based PLA Composites Reinforced With Lignin-Rich Agri-Food Wastes for Their Valorization in Industry,” Polymers 16, no. 17 (2024): 2462.
10.3390/polym16172462
CAS PubMed Web of Science® Google Scholar
59M. H. Ab Ghani, M. N. Salleh, R. S. Chen, et al., “The Effects of Antioxidants Content on Mechanical Properties and Water Absorption Behaviour of Biocomposites Prepared by Single Screw Extrusion Process,” Journal of Polymers 2014, no. 1 (2014): 243078.
10.1155/2014/243078
Google Scholar
60A. A. Mohammed, Z. Hasan, A. A. B. Omran, et al., “Effect of Sugar Palm Fibers on the Properties of Blended Wheat Starch/Polyvinyl Alcohol (PVA)-based Biocomposite Films,” Journal of Materials Research and Technology 24 (2023): 1043–1055.
10.1016/j.jmrt.2023.02.027
CAS Google Scholar
61A. Dudek and M. Klimas, “Microstructure and Mechanical Properties of Porous Ti-6al-4v Composites With Bioceramics Fabricated by Spark Plasma Sintering,” Composites Theory and Practice 14, no. 1 (2014): 23–28.
Google Scholar
62Y. P. Kwan and J. R. Alcock, “The Impact of Water Impregnation Method on the Accuracy of Open Porosity Measurements,” Journal of Materials Science 37 (2002): 2557–2561.
10.1023/A:1015460127828
CAS Web of Science® Google Scholar
63Y. Zou and J. Malzbender, “Development and Optimization of Porosity Measurement Techniques,” Ceramics International 42, no. 2 (2016): 2861–2870.
10.1016/j.ceramint.2015.11.015
CAS Web of Science® Google Scholar
64V. K. Shravanabelagola Nagaraja Setty, G. Goud, S. Peramanahalli Chikkegowda, S. Mavinkere Rangappa, and S. Siengchin, “Characterization of Chemically Treated Limonia Acidissima (Wood Apple) Shell Powder: Physicochemical, Thermal, and Morphological Properties,” Journal of Natural Fibers 19, no. 11 (2022): 4093–4104.
10.1080/15440478.2020.1853925
CAS Web of Science® Google Scholar
65I. Mawardi, S. Aprilia, M. Faisal, and S. Rizal, “Characterization of Thermal Bio-Insulation Materials Based on Oil Palm Wood: The Effect of Hybridization and Particle Size,” Polymers 13, no. 19 (2021): 3287.
10.3390/polym13193287
CAS PubMed Web of Science® Google Scholar
66J. Chaishome and S. Rattanapaskorn, “The Influence of Alkaline Treatment on Thermal Stability of Flax Fibres,” 2017.
Google Scholar
67M. A. Rahman, M. Ndiaye, B. Weclawski, and P. Farrell, “Palmyra Palm Shell (Borassus flabellifer) Properties Part 3: Insights into Its Morphological, Chemical and Thermal Properties After Alkali Treatment,” 2024b.
Google Scholar
68P. Senthamaraikannan and M. Kathiresan, “Characterization of Raw and Alkali Treated New Natural Cellulosic Fiber From Coccinia Grandis. L,” Carbohydrate Polymers 186 (2018): 332–343.
10.1016/j.carbpol.2018.01.072
CAS PubMed Web of Science® Google Scholar
69S. Shahinur, M. Hasan, Q. Ahsan, and J. Haider, “Effect of Chemical Treatment on Thermal Properties of Jute Fiber Used in Polymer Composites,” Journal of Composites Science 4, no. 3 (2020): 132.
10.3390/jcs4030132
CAS Google Scholar
70I. Elfaleh, F. Abbassi, M. Habibi, et al., “A Comprehensive Review of Natural Fibers and Their Composites: An Eco-Friendly Alternative to Conventional Materials,” Results in Engineering 19 (2023): 101271.
10.1016/j.rineng.2023.101271
CAS Web of Science® Google Scholar
71A. Karimah, M. R. Ridho, S. S. Munawar, et al., “A Review on Natural Fibers for Development of Eco-Friendly Bio-Composite: Characteristics, and Utilizations,” Journal of Materials Research and Technology 13 (2021): 2442–2458.
10.1016/j.jmrt.2021.06.014
CAS Web of Science® Google Scholar
72H. Chandekar, V. Chaudhari, and S. Waigaonkar, “A Review of Jute Fiber Reinforced Polymer Composites,” Materials Today Proceedings 26 (2020): 2079–2082.
10.1016/j.matpr.2020.02.449
CAS Google Scholar
73C. W. Nguong, S. Lee, and D. Sujan, “A Review on Natural Fibre Reinforced Polymer Composites,” International Journal of Materials and Metallurgical Engineering 7, no. 1 (2013): 52–59.
Google Scholar
74Ş. Yıldızhan, A. Çalık, M. Özcanlı, and H. Serin, “Bio-Composite Materials: A Short Review of Recent Trends, Mechanical and Chemical Properties, and Applications,” European Mechanical Science 2, no. 3 (2018): 83–91.
10.26701/ems.369005
Google Scholar
75P. B. McNulty and S. Kennedy, “Density Measurements of Grass by Toluene Displacement and Air Comparison Pycnometry,” Irish journal of agricultural research 21 (1982): 75–83.
Google Scholar
76A. S. Getme and B. Patel, “A Review: Bio-fiber's as Reinforcement in Composites of Polylactic Acid (PLA),” Materials Today Proceedings 26 (2020): 2116–2122.
10.1016/j.matpr.2020.02.457
Google Scholar
77M. Li, Y. Pu, V. M. Thomas, et al., “Recent Advancements of Plant-Based Natural Fiber–Reinforced Composites and Their Applications,” Composites Part B: Engineering 200 (2020): 108254.
10.1016/j.compositesb.2020.108254
CAS Web of Science® Google Scholar
78J. P. Manaia, A. T. Manaia, and L. Rodriges, “Industrial Hemp Fibers: An Overview,” Fibers 7, no. 12 (2019): 106.
10.3390/fib7120106
CAS Web of Science® Google Scholar
79C. A. Hill, A. Norton, and G. Newman, “The Water Vapor Sorption Behavior of Natural Fibers,” Journal of Applied Polymer Science 112, no. 3 (2009): 1524–1537.
10.1002/app.29725
CAS Web of Science® Google Scholar
80J. G. Gwon, S. Y. Lee, G. H. Doh, and J. H. Kim, “Characterization of Chemically Modified Wood Fibers Using FTIR Spectroscopy for Biocomposites,” Journal of Applied Polymer Science 116, no. 6 (2010): 3212–3219.
10.1002/app.31746
CAS Web of Science® Google Scholar
81J. Berthold and L. Salmén, “Effects of Mechanical and Chemical Treatments on the Pore-Size Distribution in Wood Pulps Examined by Inverse Size-Exclusion Chromatography,” Journal of Pulp and Paper Science 23, no. 6 (1997): J245–J253.
CAS Web of Science® Google Scholar
82K. Sacilik, R. Öztürk, and R. Keskin, “Some Physical Properties of Hemp Seed,” Biosystems Engineering 86, no. 2 (2003): 191–198.
10.1016/S1537-5110(03)00130-2
Web of Science® Google Scholar
83K. Dash, J. Nanda, S. N. Das, and V. C. Jha, “Compressive Characterization of Different Chemically Treated Borassus flabellifer Fruit Fibers,” SPE Polymers 5, no. 2 (2024): 127–135.
10.1002/pls2.10107
CAS Web of Science® Google Scholar
84D. Saravanan, N. Pallavi, R. Balaji, and R. Parthiban, “Investigations Into Structural Aspects of Borassus Flabellifer L (Palmyrah Palm) Fruit Fibres,” Journal of the Textile Institute 99, no. 2 (2008): 133–140.
10.1080/00405000701570914
CAS Web of Science® Google Scholar
85P. Jagadeesh, M. Puttegowda, S. Mavinkere Rangappa, and S. Siengchin, “A Review on Extraction, Chemical Treatment, Characterization of Natural Fibers and Its Composites for Potential Applications,” Polymer Composites 42, no. 12 (2021): 6239–6264.
10.1002/pc.26312
CAS Web of Science® Google Scholar
86X. Li, L. G. Tabil, and S. Panigrahi, “Chemical Treatments of Natural Fiber for Use in Natural Fiber-Reinforced Composites: A Review,” Journal of Polymers and the Environment 15 (2007): 25–33.
10.1007/s10924-006-0042-3
CAS Web of Science® Google Scholar
87G. P. Bernardes, M. de Prá Andra, and M. Poletto, “Effect of Alkaline Treatment on the Thermal Stability, Degradation Kinetics, and Thermodynamic Parameters of Pineapple Crown Fibres,” Journal of Materials Research and Technology 23 (2023): 64–76.
10.1016/j.jmrt.2022.12.179
CAS Google Scholar

Citing Literature

Volume7, Issue4

April 2025

e70066

Palmyra Palm Shell (Borassus flabellifer) Properties Part 1: Insights Into Its Physical and Chemical Properties

ABSTRACT

1 Introduction